In addition to the reports and JMX's noliocenter:type=info bean you can also use the NAC's JMX to search for releasecenter:type=info bean. This bean provides a method to getAllActiveReleases. You might have a look here if the reports and JMX noliocenter:type=info views do not show anything since I think these will show you active processes.
I'm honestly not sure if the view I mentioned will help you with a blocked deployment scenario. But the view will show you releases that are still active whether they have processes running or not. And if you're blocked without any processes running then it is worth a look.
If you do find something here then I would recommend taking note of the releaseId and disposing of it through the ROC. But there is a removeRelease method here too for last resort situations.
Regards,
Gregg